#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
    int n;
    cin >> n;
    int sum_b = 0;
    for (int i = 0; i < n; i++) {
        int a, b;
        cin >> a >> b;
        sum_b += b;
    }
    cout << sum_b + 1 << endl;
}